The Cardinals can position their decision to promote lefty Tyler Lyons in time to start Wednesday at San Diego as a matter of production and performance.There is also an element of protection.

Lyons, a 25-year-old Class AAA starter, will take Jaime Garcia’s next scheduled start. Garcia was officially placed on the 15-day disabled list Sunday with a tear in his left shoulder Sunday. The Cardinals selected Lyons (2-1, 4.47 ERA) ahead of disrupting the makeup of the team’s bullpen by using a reliever and over prospect Michael Wacha, who has been one of the most impressive starters in Class AAA.

Promoting Wacha this early in the season would risk sacrificing a year of cost-control on his salary, but the more pressing concern, according to general manager John Mozeliak, is the stress it could add to his young arm.

“Everybody is focused on the Wacha ‘clock,’” Mozeliak said, using the nickname for big-league service time. “The clock is something that is well-documented and it’s something that we think about.

"We also want to make sure that we don’t put him into a situation where all of a sudden we are truly having to worry about his innings and his pitch count to the degree (of) young pitchers coming up in the past. Where he’s pitching and what’s he’s learning is most important. At some point if we feel we need to go down there and tap into that to remain competitive here or to add strength at a place we feel compromised, then we’ll think about it.”

Through eight starts at Memphis, Wacha is 4-0 with a 1.89 ERA in 47 2/3 innings. That’s already more than twice as many pro innings as he threw last season. A year ago, Wacha, 21, started every Friday night as the ace of the Texas A&M staff.

Mozeliak said the preference is to give Wacha more time to get accustomed to the five-day schedule of a professional pitcher and closely monitor his innings. That is a preventative move to avoid arm trouble from increased innings. The club believes Wacha has major-league stuff but is hesitant to expose him now to major-league demands.